Cardiovascular reactions to myelography with watersoluble contrast media

Arterial blood pressure and heart rate were recorded for 5 to 7 h during myelography with iothalamate meglumine and metrizamide in 23 rabbits. After 0.6 ml iothalamate meglumine containing 280 mg I/ml a significant decrease in blood pressure and signs of circulatory failure were found. After identical doses of metrizamide and after reduction of the dose of iothalamate meglumine to 0.4 ml containing 140 mg I/ml no significant fall in blood pressure was recorded. A decrease of blood pressure was always accompanied by a decrease of heart rate. Arterial blood pressure and heart rate during experimental myelography are suggested as useful variables in the evaluation and comparison of new contrast media for myelography.